1. Field of the Invention
The invention relates generally to electron emitters and, particularly, to a surface-conduction electron emitter and an electron source using the same.
2. Discussion of Related Art
Recently, development of flat panel displays (FPDs) has increased. Flat panel displays include field emission displays (FED), liquid crystal displays (LCD), plasma display panels (PDP), etc.
Among the various types of flat panel displays, liquid crystal displays are extensively investigated, but LCDs still have problems such as low brightness and narrow viewing angle when compared with the other FPDs. For plasma display panels, high energy consumption and low color fidelity are the main obstacles.
For the field emission display panels, the most developed display type is the “Spindt” type field emission display, which typically includes a plurality of micro-tip structures. However, the fabrication cost of the micro-tip structures is high and they are difficulties in increasing the size of the display.
A recently developed field emission display is a surface-conduction electron emitter display (SED) with a plurality of surface-conduction electron emitters (SCEs) therein. In the SCE, electrons are emitted from a micro-fissure in a low work function material, such as diamond or palladium oxide (PdO). The surface-conduction electron emitter display, typically, uses one surface-conduction electron emitter per pixel. The micro-fissure, which may be only a few nanometers wide, emits electrons upon electrical stimulation. FIG. 1 shows a prior art of a surface-conduction electron emitter 10 including a cathode 12 and an anode 14 with a fluorescent layer 16 formed thereon. The cathode 12 includes a substrate 110, two electrodes 112 and 114, a conductive film 116 with a gap formed thereon, and a deposit layer 118 disposed in the gap of the conductive film 116. A nanometer scale micro-fissure 120 is formed in the middle of the deposit layer 118. In use, a voltage is applied to the two electrodes 112 and 114. Due to an electron tunneling effect, electrons emitted from the electrode 112 are transmitted to the electrode 114. An accelerating voltage is applied to the anode 14. Thus, electrons are partially deviated from the transmitting direction to the anode 14, and the fluorescent layer 16 can be excited to produce a visible light.
The low work function materials used in the surface-conduction electron emitter can be simply deposited into the gap between the electrodes by using ink-jet printing. Therefore, the method for fabricating the SED is simple and the cost is low. In a conventional 40-inch SED, the contrast is about 8600:1, the thickness is about 10 millimeters, and the power used is only half that used by a same sized LCD.
However, in the above-described surface-conduction electron emitters, the micro-fissures are generally formed using high current for a long period of time. Therefore, a large amount of energy is needed during fabrication of the surface-conduction electron emitters. Additionally, because the width of the micro-fissure is only several nanometers, a portion of the electrons emitted from one electrode reach the other electrode before the accelerating voltage can deflect them from their path. Thus, the efficiency of the surface-conduction electron emitters is relatively low.
What is needed, therefore, is to provide a surface-conduction electron emitter, in which the method for fabricating the surface-conduction electron emitter is simple, and the efficiency of the surface-conduction electron emitter is increased.